Secondhand smoke can also cause cancer in pets, studies show

This X-ray shows the chest of a cat with lung carcinoma, indicated by white arrows. Studies show that cats and dogs exposed to secondhand smoke can suffer from cancer and other problems.

LOS ANGELES — Ten years ago, Shirley Worthington rushed Tigger to the vet when the dog's mouth started bleeding. When she was told he had cancer, she knew to blame her heavy smoking, an addiction she couldn't kick until after her pet died.

Secondhand smoke can cause lung and nasal cancer in dogs, malignant lymphoma in cats, and allergy and respiratory problems in both animals, according to studies done at Tufts University's School of Veterinary Medicine in Massachusetts, Colorado State University and other schools.

The number of pets that die each year from tobacco exposure isn't available, but veterinarians know from lab tests and office visits that inhaling smoke causes allergic reactions, inflammation, and nasal and pulmonary cancers in pets, said Dr. Kerri Marshall, the chief veterinary officer for Trupanion pet insurance.

Despite Worthington's certainty about the cause of her dog's death, more research needs to be done before vets can definitively say whether a dog's cancer was caused by secondhand smoke or something else, said Dr. Liz Rozanski, whose research at Tufts focuses on respiratory function in small animals.

Worthington, 52, of Brooklyn, N.Y., said she was a teenager when she started smoking and always smoked around Tigger, who was 8 when he died in 2004. A year later, she, her mom and sister all quit in honor of the bichon frise.

Then, in 2007, Worthington's mom died while suffering from cancer.

"Cigarettes took my mother," she said. "And they took my dog."

Pets aren't mentioned in this year's surgeon general's report, but the 2006 report said secondhand smoke puts animals at risk. The Legacy Foundation, the nation's largest nonprofit public health charity, encouraged smokers to quit for the sake of their pets, and the American Society for the Prevention of Cruelty to Animals urged making homes with pets smoke free.

It's even more important to safeguard cats, which are more susceptible to tobacco smoke than dogs.

Lymphoma is one of the leading causes of feline death. The Tufts research showed that repeated exposure to smoke doubled a cat's chances of getting the cancer and that living with a smoker for over five years increased the risk fourfold. It can also cause a fatal mouth cancer.